The BBC celebrity's next-door neighbour heard her scream before rushing to the door to find her slumped on the step. She was unconscious and covered in blood. A post-mortem examination last night revealed a single gunshot wound to the head.
Last night, as tributes poured in for a television presenter whose immense popularity was based on her down-to-earth appeal, police said they were investigating whether Ms Dando, 38, had been killed by a stalker. Only last year, police were called to deal with an obsessive fan who was tormenting her with phone calls and letters, though he is not suspected of having anything to do with yesterday's events.
Ms Dando, who had recently announced her engagement and was preparing for the wedding in September, was attacked late yesterday morning as she returned to her house in Fulham, west London. Her assailant struck seconds after she stepped out of her car.
An ambulance crew was called to the scene and struggled to revive her before she was transferred to Charing Cross Hospital. She died a little over an hour later, at 1.03pm. Her fiance, Alan Farthing, was called to identify the body.
Richard Hughes 32, a financial trader who lived next door to the Crimewatch and Holiday programme presenter, said he had been upstairs when he heard her pull up outside and activate her car alarm. "Forty seconds later, I heard a scream ... She was completely unconscious and covered in blood. I took a look at her, she was not breathing. Somebody called the emergency services."
Police immediately launched a massive hunt for Ms Dando's killer, with three dozen officers involved in house-to-house inquiries. Yesterday evening they sealed off a section of Thames riverbank at Putney, where there were reports that someone may have flung something into the bushes. Police confirmed they had found an object - possibly a weapon - but it was not clear whether they were linking it to the killing.
Detective Chief Inspector Hamish Campbell, leading the investigation, said police were investigating every possibility including the prospect that Ms Dando had been the victim of a stalker.
Tributes to Ms Dando, were led yesterday by Tony Hall, chief executive of BBC News. He said: "Everyone in BBC News is devastated. She was a wonderful person to work with and was respected and trusted by millions."
The murder was even discussed in the Commons with tributes from the Home Secretary and shadow Home Secretary. Other tributes were made by the Queen and Tony Blair.
Ms Dando's brother, Nigel, a reporter on the Bristol Evening Post, said he learnt of the tragedy after deciding to investigate early reports of an "incident" involving his sister. He said the news had come as a "huge shock" both to himself and his widowed father.
Martyn Lewis, a colleague on the Six O'Clock News, added: "Bewilderment, tears and quiet anger fill the BBC newsroom today."
Nick Ross, her co-presenter on Crimewatch, said: "It's just so terrible. She was a smashing person. You could not say anything bad about her."
Ms Dando was at the peak of her career. Despite stepping back from newsreading and handing over the lead role in the Holiday programme, her new Antiques programme was due to be broadcast on Sunday. Advance publicity for the show saw her posing on the front of the Radio Times, clad in a leather catsuit in front of an Aston Martin.
Last night, detectives had taken away Ms Dando's car, a BMW convertible, as scene-of-crime officers scoured the area outside her house for possible clues. Officers last night erected an incident tent as they continued to work throughout the evening. Detectives confirmed there was no sign of a forced entry at the house and there was nothing to link the attack to her work with Crimewatch.
Earlier this year, at a reception to mark the 10th anniversary of the programme, Ms Dando admitted she had been concerned about her personal safety after taking the job. During one interview, she said: "It upsets me that there are such brutal people ... I take great care over home security and about walking home in the dark. But I also know that crimes are very rare."
Police said they were looking for a dark-haired man in his late thirties to early forties. He was smartly dressed and carried a mobile phone.